Casting roller with variable profile for casting metal strip in a casting roller plant

ABSTRACT

The invention relates to a casting roller for the casting of metal strip in the casting gap between two parallel casting rollers with variable separation and which may be cooled. A shaft ( 1 ) with a shell ( 2 ), surrounding the above at a separation therefrom and an external cover ( 3 ), the circumferential surface of which may be adjusted with regard to the crowning thereof during the casting operation, for altering the shape of the external cover, are disclosed. Annular pressure chambers ( 3   c ) are thus formed on the inner side of the shell ( 2 ) for hydraulically pumping the above up, which are formed between the shells and applied strips ( 13 ). The casting roller further comprises means for connecting the annular pressure chambers ( 3   c ) to an external hydraulic pressure generating system.

[0001] The invention relates to a casting roller for the casting of metal strip in the casting gap between two variably spaced parallel and coolable rollers.

[0002] Casting rollers are known with drives by means of a stationary motor, transmission and universal joint shaft with a rotating shaft. A drawback of this type of construction is that the replaceability of the casting rollers is possible only from one side. For this purpose, the casting rollers must be decoupled from the drive unit in an expensive manner.

[0003] Another type of construction resides in the connection of a casting roller shaft with an annular torque motor which rotates with the shaft of a casting roller relative to its stationary axis. The drawbacks of this construction is the relatively complicated internal configuration of the casting roller which requires dynamic seals for the supply of a coolant.

[0004] The document EP 0 900 607 A1 describes a casting roller with an outer shell connected with a drive shaft. A plurality of individual elements are provided within the roller shell in order to adjust the contour of the outer shell. The drive shaft passes through a support element of large diameter and is connect d with the outer shell by means of epicyclic transmission elements. The adjustment elements are effective between the inner side of the outer shell and the support tube which is massively configured as the primary structural element to be capable of absorbing the reaction forces of the adjustment elements.

[0005] The document DE 197 37 117 A1 describes the double roll casting of metal strip, especially ferrous metal strip. The outer surfaces of the casting roller, which define the casting gap, are cooled by longitudinally extending cooling water passages. The cooling water is supplied to the passages of each roller through radial passages in an end wall of the casting roller and from the longitudinal passages flows through further radial passages in the opposite end wall of the casting roller to be discharged. The cooling water travels through all of the longitudinal passages of a respective casting roller in one longitudinal direction and through all of the longitudinal passages of the other casting roller in the opposite longitudinal direction.

[0006] The document EP 0 680 795 A1 describes rollers journaled a roller stub shafts for an apparatus for the continuous casting of metal strip. Each casting roller is provided with an outer shell of a material which is a good thermal conductor and which in a cooling sector has the solidification heat abstracted from the liquid metal and a central core extending into the roller stubs, whereby cooling channels run through the shell parallel to the roller axis and are supplied with a cooling medium, especially water. Cooling medium tubes are arranged at the ends of the casting rollers to enable an adjustable cooling agent distribution to the cooling channels.

[0007] The document EP 0 390 924 B1 describes an apparatus for the continuous casting of a metal strip whereby the apparatus has the following:

[0008] A pair of internally cooled cast rollers which rotate in opposite directions to one another and are arranged parallel to one another and a pair of sealing barriers of refractory material which are arranged on both sides of the casting roller pair to form together with the peripheral surfaces of the casting rollers, a casting vessel for holding the molten metal. The molten metal is continuously cast through the roller gap to form the metal strip. The document DE 199 19 354 A1 describes a double roll casting machine for the casting of metal strip with a pair of horizontal casting rollers. A pair of side plates are in engagement with the end surfaces of the casting rollers to form lateral limits for the cast strip. A pair of side plate holders fix the plates and shifting devices apply the requisite closure forces to the side plates. The shifting devices are connected with the side space rollers by pivot connections which are formed by horizontal pivot pins and vertical pivot pins in order to enable the side plates to orient themselves to the roll ends by pivotal movements both longitudinally and laterally while restricting the plates from a rotation.

[0009] The document EP 0 903 191 A2 discloses a device for the continuous casting of metal strip comprising a pair of parallel casting rollers to which a metal melt is delivered. The casting rollers ar arranged on slides, shiftable on a fram to enable the casting rollers to be moved toward one another and away from one another.

[0010] The document EP 0 471 731 B1 describes a double roller strip casting machine with a pair of side barrier arrangements which border on the opposite ends of the casting rollers, whereby each of the side barrier arrangements has a lining segment carried by a support plate and composed of refractory material as well as means for oscillating the arrangement. The lining segments of the side barrier arrangements are in contact with the ends of the casting rollers. The oscillating means oscillates both arrangements parallel to the strip casting direction while the lining segments remain in contact with the ends of the cast rollers.

[0011] The document DE 33 36 692 C2 describes a method of continuously casting metal sheet with a pair of parallel casting rollers which delimit a rolling gap and are internally cooled by a liquid and which come into contact directly with the enclosed metal. The circumferential area of each casting roller has in the starting state a negative camber [crowning]. Upon commencement of the continuous casting process, a pressure is applied to an inner region of each roller so that the outer surfaces of both casting rollers assume a truly cylindrical form. The pressure applied to the internal region of a casting roller reduces as a consequence of the heating of the outer circumferential surfaces of the cast rollers by the molten metal during the progress of the continuous casting so that the outer circumferential surface of each of the casting rollers becomes linear and has the form of a true cylinder without any thermal camber or crowning. Structurally this is achieved by a roller spindle which through an inner shell applied over the spindle can produce a negative camber or crowning at the outer surface of an outer shell applied over the inner shell and having cooling channels on its internal peripheral surface, and through a hydraulic pressure chamber in the axial middle region of the inner peripheral surface of the inner shell and which is connected controllably with a liquid pressure source.

[0012] The U.S. Pat. No. 4,811,780 A discloses a continuous casting apparatus for a metal strip in which a pair of casting rollers rotate in opposite directions to one another and the casting rollers have respective horizontal axes which are opposite to one another. Furthermore, the casting device is provided with a pair of lateral barriers which are spaced apart advantageously in accordance with the widths of the strip to be cast so as to form on the circumferential surfaces of the casting rollers, a metal reservoir the metal strip is continuously cast through the gap with the casting rollers from the molten metal of the metal reservoir. The lateral barriers are so arranged that at least a part thereof contacts the circumferential surface of each casting roller. The lateral barriers are made from refractory material and have a sufficient wear resistance. The circumferential surface part of the casting roller which is contacted by the lateral barrier is formed with a roughened surface with polishing properties.

[0013] Starting from the aforedescribed state of the art, th invention has as its object to provide an external shell which can so influence the casting gap defined by the casting rollers in the casting process that the casting strip has a predeterminable and reproducible positive or negative camber or crowning. Furthermore, it is an object to provide the journaling of the casting rollers and their media connections and drive arrangements such that a rapid replacement of the casting rollers is possible in a brief period of time and so that, in addition, different thermal expansion in the casting roller is completely compensated by the configuration of the cooling system.

[0014] The solution of these objects is achieved with a casting roller of the type set out in the preamble of claim 1, in accordance with the invention, with the aid of a shaft surrounded at a radial spacing by a sleeve and an outwardly lying shell with adjustable crowning or camber in casting operation of its peripheral surface and at least one annular pressurizable chamber which can be hydraulically pumped up and is located between the sleeve and the cast roller shell, as well as with auxiliary means for connecting the annular pressure chambers to an external hydraulic pressure generating system.

[0015] The crowning or camber of the casting roller can be adjusted in a highly precise manner because of the arrangement of the pressure chambers on the periphery of the sleeve to maintain a desired cast strip profile.

[0016] A cooling of the roller shell in opposite directions according to the invention prevents different radial thermal expansions of the roller shell from right to left or conversely. Furthermore, with the drive according to the invention of the casting roller shaft by means of the annular torque motor, a rapid replacement of the casting rotor is enabled and thus the time required for each replacement is shortened. The reproducibility of the amount of crowning or chamber imparted to the roller can be set by the magnitude of the pressure in the hydraulic system.

[0017] The pressure medium supply for the hydraulic expansion of the annular pressure chambers which is required can be effected through the shaft at the end thereof at which the cooling water supply is provided so that the annular torque motor can be arranged at the other end of the shaft.

[0018] Further details, features and advantages of the invention are given in the following description of an embodiment which has been schematically shown in the drawing.

[0019]FIG. 1 shows in a perspective and partly sectional illustration the interior structure of the casting roller.

[0020]FIG. 1 shows that the camber or crown profiling effect is enabled by hydraulically pumping up annular pressure chambers 3 c on the inner side of the sleeve 2 on which are formed between the sleeve 2 and bands 13 set thereupon. The bands 13 deformed by pressure produce a force upon the annular pressure chambers [sic Translator's note: should be: comb 3 c of the shell 3] and thus deform the shell 3 to produce the camber. The annular pressure chambers can be so configured that these effect a torque transfer from the drive shaft to the casting roller shell 3.

[0021] The radial comb members 3 c supporting the casting roll shell 3 can have at least partial undercuts to enable elastic force equalization in the adjustment of the crowning or camber.

[0022] The rapid replaceability of the casting roller is realized through the provision of the annular torque motor 6 on the shaft 1 and the water feed and discharge fittings on the water clamping plate 14. The oil supply required for influencing the profile of the cast roll shell is effected through the shaft 1 opposite the water supply and discharge fittings 14 a and 14 b. Thus the connections for the hydraulic medium and the connections for the feed and water discharge are all arranged on one and the same side of the shaft 1.

[0023] The opposite flows of the coolant through the casting roller is effected from left to right through the cooling bores 3 a. The cooling water flows through the water clamping plate 14 a into the space between the bore 1 a in the shaft 1 and the tube 7, further through radial bores in the shaft part of the shaft 1 b, further through radial slits in ring 9, through cooling bores 3 a, through the slit 12, through the ring 11, through the axial bores 2 a of the sleeve 2 set onto the shaft 1, through the ring 10 and the radial bores 1 c of the shaft 1 as well as through the tube 7. The cooling water exits through the water clamping plate 14 b.

[0024] Because of the aforedescribed arrangement of the cooling water feed in the cast roller, the cooling water traverses the respective casting roller in both flow directions equally over respective paths. The important compensation for different thermal expansions of the casting roller is thus complete achieved. The casting roller according to the invention is, as a consequence of its profile-influenceable construction, suitable extraordinarily advantageously for use in a strip casting plant with casting rollers because of the counterflow coolant passage therethrough and the rapid replaceability. 

1. A casting roller for casting of metal strip in a casting gap between two variably spaced parallel and coolable casting rollers, characterized by: a shaft (1) with a sleeve (2) surrounding it with a radial spacing and an outwardly lying shell (3) with an adjustable crowning or camber of its peripheries during casting operation, and at least one annular pressure chamber (3 c) which can be hydraulically pumped up and which is formed between the sleeve (2) and the shell (3) and with means for connecting the annular pressure chamber (3 c) to an external hydraulic pressure generating system.
 2. A casting roller according to claim 1 characterized in that in the interior of the casting roller, bands (13) are arranged which are deformable by high hydraulic pressure and apply their force components to radial combs which then produce a crowning or cambered deformation of the shell (3) of the casting roller (1).
 3. The casting roller according to claim 1 or claim 2 characterized in that the extent of the crowning or camber deformation is reproducibly adjustable by the measure of the pressure level in the hydraulic system.
 4. The casting roller according to one of claims 1 through 3 characterized in that for the casting roller a journaling with fixed side and releasable side mounting pieces (4,5), is provided on the end shaft stools (7, 7′).
 5. The casting roller according to one or more of claims 1 through 4 characterized by a drive device in the form of an annular torque motor (6) in a rotationally fixed connection with the shaft stub (7) located opposite the cooling medium feed and cooling medium discharge fittings (14 a, 14 b).
 6. The casting roller according to one or more of claims of claims 1 through 5 characterized in that the casting roller (1) has cooling medium bores (2 a, 2 b; 3 a, 3 b) traversed in axially opposite directions and which are connected by radial bores (1 a, 1 b) or radial slits in rings (9,10; 11, 12) with one another in a flow-through connection.
 7. The casting roller according to claim 6 characterized in that cooling agent bores (2 a, 2 b; 3 a, 3 b) are dimensioned to have equal lengths in both flow directions for the respective casting rollers.
 8. The casting roller according to one or more of claims 1 through 7 characterized in that a connecting element is provided for the feed and discharge fittings (14 a, 14 b) for cooling water of a cooling water flow system in the form of a clamping plate (14).
 9. The casting roller according to one or more of claims 1 through 8 characterized in that pressurized oil feed required for the hydraulic expansion of the annular pressure chamber is provided with a closure element which is arranged opposite the cold water feed in the region of the one shaft stool (7).
 10. The casting roller according to one or more of claims 1 through 9, characterized in that the casting roller is arranged on a stationary shaft (1).
 11. The casting roller according to one or more of claims 1 through 9, characterized in that between the casting roller shell (3) and the casting roller shaft, pressure chambers are provided for torque transmission.
 12. The casting roller according to one or more of claims 1 through 11, characterized in that the casting roller shell (3) is braced by radial combs (3 c) at least partly having undercuts. 